New Zealand captain Richie McCaw says he expects Australia to be a tougher challenge than South Africa as the All Blacks (4/11 to beat the Wallabies) look to keep their perfect Tri-Nations record going.

So far New Zealand have breezed past the Springboks twice in their quest to win their tenth Tri Nations crown.

Victory on Saturday in Melbourne could effectively seal the southern hemisphere title for the All Blacks as they already sit six points clear of their two rivals at the top of the table.

Graham Henry’s boys will be hopeful of keeping their great record against Australia in tact as they go in search of an eighth straight win against the Wallabies.

Australia (5/1 outright tournament winners) remain in the hunt for the Tri Nations after their 30-13 victory over South Africa (66/1) last week.

McCaw says he is expecting a tough game, but has backed his side to come out on top in the Bledisloe Cup contest.

“The Wallabies are going to be a different challenge and I think they’re going to be a better challenge for us,” he said.

“They’re going to be a tougher opponent than what we’ve faced so far so we’re going to have to be right on the job.”